Punch and stripping means



June 13, 19339 G. F. WALES PUNCH ANDISTRIQPPING MEANS Filed April 19, 1932 INVENTOR.

Patented June 13, 1933 UNITED STATES GEORGE E. WALES, OF BUFFALO, NEW YORK PUNCH AND STRIPPING MEANS Application filed April 19, 1932. Serial No. 606,126.

My invention relates to a punch and stripping unit which is more particularly mtended for use in connection with the punchlng and stripping mechanism of stamping and" 'rcsrstance of a predetermined strength is 55 similar presses although the same may also be employed advantageously in other installations.

In the punching and stripping mechanisms of stamping presses as heretofore constructed, the punch has been held in position by means of a punch holder plate made to accommodate it, which plate has been rigidly fastened to the main shoe or holder by means of screws and dowel pins, the punch having a head larger than the body to prevent from pulling out of the plate. In order to eliminate the necessity for removing the punch holder plate when changing punches, certain so-called removable punches have been 1nvented which permit the punch to be removed or secured in place readily from the operating side of the punch holder plate and it is with these punches that the present 111- vention is more particularly adapted. In all punch projects from the punch holder plate a suflicient distance to allow space for a stripping device to surround the working end of the punch. The device most commonly employed heretofore has consisted of a strlpper plate assembled around the punch and held in position by springs interposed between the stripper plate and main shoe or holder to supply the force for stripping the work from the punch, which springs have been placed under compression bv means of screws projecting through and suspended from the main holder, the screws also acting as guides to hold the stripper in place and under continuous spring pressure. It has therefore been necessary to remove the entire unit from the press in order to replace a defective punch because the stripper plate had to be removed before the punch could be changed and this has caused unnecessary loss of time and undue expense.

It is the object of this invention to provide a self-contained stripping unit which can be readily and conveniently assembled types of punch holding mechanisms the with and removed from the punching mechanism without disturbing any other part of the mechanism or causing it to be removed from the press; to provide a self-contained stripping unit for punches in which a spring built up as a unit so that the spring element is under load when same is assembled with retaining means, said load being of suiiicient capacity to strip certain gauges of work from the punch and to be so calibrated; to make said stripping unit so that when same is used with the so-called removable types of punches, the same tool or pry used to release the punch from its retainer can first be used to release the stripping unit from the punch; to provide a self-contained stripping unit of such construction that punches already in use which have not been so fabricated, can be prepared to receive said stripping unit by the expedient of grinding or routing out a seat to receive the locking element of said stripping unit; to provide a semi-finished stripping unit so that the final operation of making the opening through which the cutting section of the punch is to work can be done at a time subsequent to the assembling of the unit without disassembling any of its parts; and to, provide a stripping device which is simple in construction. thoroughly reliable and eificient in its purpose and inexpensive to manufacture and install.

These objects and the several novel features of the invention are hereinafter more fully described and claimed and the preferred form of construction by which these objects are attained is shown in the accompanying drawing, in which Figure 1 is a fragmentary vertical section of a stamping press showing an approved form of punch and self-contained stripping unit embodying my invention ina retracted or inoperative position.

, Figure 2 is a fragmentary vertical section of the same stamping press but showing the same in operation.

Figure 3'is a view of the punch as it appears with the stripping unit removed showing an approved form of seat for the locking element.

Figure 4 is a fragmentary view, on an enlarged scale, of the locking element as it appears assembled with the upper abutment disk and tubular neck and the groove in which the spring or split ring for holding the locking element in place operates and also shows the clearance slot in the tubular neck through which the locking element extends.

Figure 5 is a plan view of the locking element retaining spring.

Figure 6 is a vertical side elevation of the tubular neck.

Figure 7 is a vertical rear elevation of the abutment disk showing the flange closed in to prevent the locking element split ring from turning.

Figure 8 is a fragmentary vertical section of a stamping press showing a stripping unit similar to that in Figures 1 and 2 but with a tightening collar threaded on the abutment disk.

In the following description the reference characters indicate like parts in the several figures of the drawing.

Although this invention is capable of use in various installations the same is shown in the present case in the drawing as used in connection with the punching and stripping mechanism of a stamping press of the kind connnonly used for blanking, piercing, trimming, punching, and notching sheet metal. It is obvious that the stripping unit described in the drawing may be used with various styles of punches and stripping mechanisms and that the locking element construction may be used with other types of strippers and mechanisms, being varied in detail to suit conditions.

The numeral 10 represents the punch holder or body ofthe means whereby the punch is supported upon the vertically movable slide or -arrier of the press in which my invention is embodied and 36 represents the die holder or body which is adapted to be mounted on the stationary bed of the press and upon which is supported the die which cooperates with the punch on the slide or carrier.

To the under side of the punch holder is detachably secured the punch shoe 11 whereby the punch is dctachably mounted on the punch holder as shown in Figures 1, 2, and 8.

The punch 13 in the present case may be socured to the punch shoe in any manner known tothe art as that part of the punch embodied in my invention is the part which projects outside the punch shoe in which 15 represents an angular depression formed in the punch having a seat 14 which receives the locking element, of the stripping unit as will appear later on. That part of the punch body which extends outside of the punch holder plate is made accurately to size to receive the stripping unit which is constructed as follows The numeral 28 represents an upright tubular neck which in this instance forms the central section of the stripping unit and also acts as a guide, the opening 15 bcinghccuratcly made slightly larger than the body of the punch 46 while at its lower end this tubular neck is provided with another opening slightly larger than the working end of the punch thus permitting this tubular neck and punch to slide one upon the other. The body of the tubular neck is provided at its lower end with an external screw thread 30 which engages with an internally threaded opening in the bearing disk 32 while at its upper end a laterally formed external collar provides a downward facing shoulder 231 below which an elongated vertical slot 29 slightly wider than the thickness of the locking element 16 extends downward for the purpose of permitting the locking element to pass through the slot and to engage with the depression in the punch body without being interfered with by the vertical movement of said tubular neck while at the same time it prevents rotation of the tubular neck when the element is in engagement with the seat in the unch.

A bearing disk 32 is mountet on the threaded part of this tubular neck and is held in a dcfiniteposition thereon by engaging its inner side with the innermost thread 31 of said tubular neck and an opening 33 is provided on the vertical center line of the slot 29 of the tubular neck which provides accessibility to the locking element for a pin or pry when said locking element is to be released. The inner or uppermost central part of said bearing disk is provided with a shoulder to provide a centering means for a spring 100 to be mentioned later.

The upper section of this stripping unit consists of an abutment disk or sleeve 21 which embraces the external collar 26 of the tubular neck. At its lower or innermost end this 105 abutment disk 21 has a downwardly extend-v ing neck so as to form an internal upwardly facing shoulder 23 which is adapted to be engaged by the shoulder formed by the inner side of the collar 26 on the tubular neck 28 for 110 the purpose of limiting the separation of the these sections, while at its upper end said abutment disk is provided with a lateral] y projecting external flange 41. Through the lower wall of this abutment disk a slot is provided, 115 the upper side of which forms the two angular faces 19 and 201, said slot being slightly wider than the thickness of the locking element 16 which it accommodates. Around the lower portion or neck of this abutment disk a groove 120 24 is provided a fixed distance away from the face 201 for the purpose of retaining the locking element in place as will now be explained.

Although various means may be provided for detachably mounting the stripper unit on 125 the punch, those shown in the drawing are preferred and comprise a locking element 16 having opposed faces 141 and 20 which coact with the seat 14 of the depression in the punch and the face 201 of the abutment disk 21 in such manner that a brace or support is formed to hold the abutment disk in a fixed vertical relation to the punch and punch shoe 11. The groove 24 in the abutment disk 21 receives a split ring or spring 18 which extends through an opening in locking element 16 at a location which causes the split ring to exert an inward pull on said element and this pull is converted entirely to the lower face 141 because of the extension 291 bearing against the opposed notch in abutment disk 21 which causes the element to fulcrum about said notch, the split ring extending or contracting when an outward force is applied to or released from the lower inside portion of said element 16.

The locking element extends through the slot 29 in the tubular neck 28 and inwardly a suflicient distance to cause the lower face 141 to spring outwardly when it is being assembled over the punch until said face engages with the depression in the punch when it snaps into said depression and retains the stripping unit in its properposition on the punch with the abutment disk bearing against the punch shoe 11. When it is desired to remove the stripping unit from the punch a tool or pin is inserted through the opening 33 in bearing disk 32 until it engages the projection 17 on the lower side of the locking element which can then bepried out of engagement with the punch depression and the stripping unit withdrawn.

A split ring 18 holds the upper face 20 and the extension 291 of the locking element 16 securely in their co-acting notches in the "abutment disk 21 because the opening in the element through which the split ring passes is slightly lower than the groove in the abutment disk in which the ring acts, thus causing an upward pressure of the element against the faces of the notch.

Surrounding the neck of the abutment disk 1 and tubular neck sections, 21 and 28, is a spring resistance having preferably the form of a helical spring 34 which bears at its 0pposite ends against the inner side of the hearing disk 32 and the inner side of flange 41.

In assembling this stripping unit the locking element '16 is first assembled with the abutment disk 21 by means of the split ring 18. The groove 24 on the opposite side of the abutment disk from the locking element is then closed in as shown at 39 in Figure 7 to prevent the ring from turning in its groove. The tubular neck 28 is then pushed through the abutment disk and turned until the locking element snaps into the groove 29 in which position the'tubular neck and abutment disk can slide one upon the other but cannot rotate one upon the other. The spring 34 is then placed around the abutment disk and tubular neck assembly and the ends of said spring engaged with the flange 41 of the abutment disk and the bearing disk v 32 which is then screwed on the tubular neck until it engages with the innermost end of the thread which latter serves as a stop to limit this inward movement of the disk on the tubular neck thereby contracting the spring so as to impose a load or compression thereon the )ressure of which may be determined by ca ibration so that all units similarly constructed and assembled will have a known spring resistance. It is in this form that the stripping unit is supplied to the user, except in certain instances the lower 0 ning 35 in the punch tube 28 may be omitte to be put in by the user when the size and shape of the opening is decided upon.

If, now, during the operation of the press in which these parts are mounted, the stripping un t is moved inwardly relatively to the respective punch and its holder, the tubular neck and abutment disk will slide lengthwise one upon the other and thereby increase the compression upon the spring while the unit is in engagement with the work piece which is be ng operated upon, the abutment disk re maining in constant relation to the punch because of its bearing against the punch shoe at surface 12 Figure 2. As the press opens and the punch moves away from the die the stripping unit will be projected by the spring an extent sufiicient to engage the shoulder in the neck of. the abutment disk with the collar 26 of the tubular neck and thereby prevent further expansion of the spring.

In Figure 8, sleeve 21 is provided with an external thread 48 which engages with the internal thread in collar 47. Thus if the distance from face 12 of punch shoe 11 to seat 14 of the punch varies, the collar is turned until all play is removed from between said punch shoe and abutment disk 21 and thus locks the unit tightly in place. Because of the wedging action of the locking element when this collar is tightened it is necessary to loosen it before the pry is inserted for removing the unit from the punch.

Although the form shown in the drawing represents a practical embodiment of my'invention it is to be understood that the same may be varied as-to details and still contain the essence of my improvements as summed up in the following claims What I claim and desire to secure by Letters Patent of the United States is:

1. A punch and stripper assembly comprising a punch, a punch shoe mounted on a punch holder, and a stripping unit, including a lower bearing disk, a tubular neck projecting upwardly from said bearing disk and embracing said punch, an upper abutment disk engaging the under side of said punch shoe and havin a downwardly projecting tubular neck, said necks being telescoped and having cooperating shoulders for limiting the separation of said bearing and abutment disks, a spring under compression interposed between said bearing and abutment disks being held central at one end by the neck of said abutment disk and at the other end by a' shoulder on said bearing disk, said bearin disk having a screw connection with said tu ular neck, means for detachably mounting said stripping unit on said punch 1n eluding a locklng element guided in a slot in said abutment disk and extending through an 0 )eniug in said tubular neck, one end of said ocking element engaging a seat in said punch while the opposite end engages and fulcrums on a seat in said abutment disk, said element being yieldingly held in its innermost position by means of a split ring extending through an opening in said element and acting in an annular groove around the neck of said abutment disk, said groove being closed in at the opening between the ends of said ring. aml means for permitting the release of said stripping unit from said punch including an opening through said bearing disk, on the same vertical eenterline as the locking element which element is provided with a seat or extension, said opening permitting the insertion of a pin or pry which, when inserted through said opening and engaging with said extension is enabled to lift the element out of the seat in said punch and thereby permit the stripping unit to be removed from the punch without disturbing said punch or punch holder.

2. A punch and stripper assembly comprising a uneh, a punch shoe mounted on a punch iolder. and a stripping unit, including a lower hearing disk, a tubular neck projecting upwardly from said bearing disk and embracing said-pimch, a collar engaging the under side of said punch shoe having an internal screw thread, an upper abutment disk having an external thread engaging the internal thread of said collar aml also a downwardly projecting tubular neek, said necks being teleseoped and having co-operating shoulders for limiting'the separation of said bearing and abutment disks, a spring under compression interposed between said bearing and abutment disks being held central at one end by the neck of said abutment disk and at the other end by a shoulder on said bearing disk, said bearing disk having a screw connection with said tubular neck, means for detachably mounting said stripping unit on said punch including a locking element guided in a slot in said abutment disk and extending through an opening in said tubular neck, one end of said locking element engaging a seat in said punch while the opposite end engages and fulcrums on a seat in said abutment disk, said element being yieldingly held in its innermost position by means of a split ring extending through an opening in said element and actin in an annular oove around the neck of said abutment dis said groove being closed in at the opening between the ends of said ring, and means for permitting the release of said stripping unit from said punch including an opening through said bearing disk on the same vertical centerline as the locking element which element is provided with a seat or extension said opening permitting the insertion of a pin or pry which, when inserted through said opening and engaging said extension, is enabled to lift the element out of the seat in said punch and thereby permit the strip ing unit to be. removed from the punch wit out disturbing said punch or punch holder.

3. Apunch and stripper assembly comprising a punch, a punch shoe mounted on a punch holder, a detachable self-contained stripping unit, a spring-impelle l punch lock borne b said stripping unit, and means for permitting the insertion of an instrument for withdrawing said lock against the tension of its impelling sprin".

4. A punch and stripper unit assembly comprising a punch, a punch shoe mounted on a punch holder, a detachable self-contained stripping unit embracing said punch and bearing against said punch shoe, a, springnnpelled punch lock borne by said stripping unlt, and means for permitting the insertion of an instrument for withdrawing said lock against the tension of its impelling spring.

5. A punch and stripper unit assembly comprisin a punch, a punch shoe mounted on a punch older, a detachable self-contained stripping unit embracing said punch and having an adustable collar bearing against said punch shoe, a spring-impelled punch lock borne by said stripping unit. and means for permitting the insertion of an instrument for withdrawing said lock against the tension of its impelling spring.

In testimony whereof I hereby aflix my signature.

GEORGE F. WALES. 

